For everybody using the Configuration suite of Microsoft, and in more detail:
System Center Configuration Manager (SCCM)
System Center Operations Manager (SCOM)
System Center Data Protection Manager (DPM)
System Center Virtual Machine Manager (SCVMM)
And some more...
All these products are bundled with an installation of msSQL standard.
And can share the same Microsoft database free from charge (you already paid for it).
Keep this in mind when you talk to your licensing department and/or counting SQL instances for billing.

System Center Essentials is not include in this rule!
Some Rules to follow
First thing is that the database cluster may not contain anything else but product of the Configuration suite.
Also a little database just for your own testing or in house made product, no go!
Second is that you use SQL standard, not enterprise or other...
Standard you can still make a passive failover.
Last one, do not put the DPM database there, not because of license.
But if your cluster fails, where are you going to recover from??? ;-)
For more info read here>>>